Apparatus and method for taking dental impressions



Au w, 1937. A. K. SIMMONS 2,089,715

APPARATUS AND METHOD FOR TAKING DENTAL IMPRESSIONS Filed Dec. 29, 1933 4 Sheets-Sheet 1 Aug. 10, 1937. A. K. SIMMONS 2,089,715

APPARATUS AND METHOD FOR TAKING DENTAL: IMPRESSIONS Filed Dec. 29, 1933 4 Sheets-Sheet 2 Aug 1937- A. K. SIMMONS 2,089,715

APPARATUS AND METHOD FOR TAKING DENTAL IMPRESSIONS Filed Dec. 29, 19:53 4 sheets-sheei. s

Au 10, 1937. A. K. SIMMONS 2, 7

' APPARATUS AND METHOD FOR TAKING DENTAL IMPRESSIONS Filed Dec. 29, 1955 4 Sheets-Sheet 4 Patented Aug. 10, 1937 UNETED STATES PATENT QFFICE My invention relates to dental impression apparatus and the method of operating the same. It is the primary object of my invention to provide an apparatus for producing a more accurate impression and for obtaining such an impression more quickly and easily than has been heretofore possible. In making in the usual moval of the After the usual type of tray has been removed from the patients mouth, it is necessary for the dentist to estimate the position of the teeth within the plaster, and to cut into the plaster toward the incisal portion of the teeth, dividing the plaster cast into various sections. to properly estimate the division lines between the various sections, often necessitating a number of impressions to be made before a proper cast can be made. cutting through the plaster into the gums resulting in discomfort to the patient and bleeding. This miscalculation of the division of the cast into sections also delays the removal of the plaster from the mouth of the patient for long periods of time, often resulting in nausea of the patient. Such nausea makes necessary prompt removal of the plaster in the quickest manner, ordinarily making necessary an entirely new impression.

Unless the sections of the cast are properly cut, the cast is broken up into a large number of sections in the removal, making difficult the assembly of these sections to form the complete impression.

this separation. of the process, however, is the proper removal of the plaster from the patients mouth. Due to the fact that the teeth, particularly the molars, are larger at the middle third than at the surface of the gums, and due to the various angles at which the teeth project in the mouth, the re- APPARATUS AND METHOD FOR TAKING DENTAL IMPRESSIONS Alfred K. Simmons, Victoria, Minn, assignor, by direct and mesne assignments, of thirteen per cent to Jorgen M. Simmons, Minneapolis, Minn., and fifty-one per cent to said Alfred K. Simmons, and twenty-four per cent to Knnte N. Simmons and twelve per cent to Marie B. Simmons, both of Minneapolis, Minn.

Application December 29, 1933, Serial No. 704,459

7 Claims. (01. 321'7) culties. My impression trays are provided with a removable portion which is embedded into one portion of the cast. This removable portion is threadably connected to the remaining portion of the tray with a bolt or pin extending through the outer surface of the tray. By this bolt, the removable section can be separated from the tray, thereby separating the entire impression from the tray. It is my purpose to provide a series of impression trays graded in size from which the dentist may select a tray of proper size to best fit the patients mouth. Each tray is provided with internal ribs which divide the impression into a number of sections. When the tray is removed, the plaster impression is divided by a series of grooves into sections. An instrument may readily be inserted in these grooves, breaking apart the impression along the grooves. As the outer surface of the impression has not been mutilated, the impression may readily be reassembled in the tray from which the impression was made. The impression can thus be made in a minimum of time as the line of cleavage between the sections has been determined by the position of the ribs Within the tray.

It is also my object to provide a removable flexible attachment for the distal palatal border of the upper tray to close any opening between the border to the tray and the palate of the patient, preventing any plaster from entering the patients throat.

It is also an object of my invention to provide a means of gripping and holding the various trays, to facilitate insertion of the trays, the removal thereof from the patients mouth, and the holding of the trays in proper position during the setting of the plaster or other impression material.

While I have referred to my trays as being particularly adapted for the casting of plaster impressions, I desire to have it understood that my trays can also be used, in the same or modified forms, for other material, such as modelling wax or the like. For example, my trays can be readily adapted for the formation of wax trays used to provide an impression of the mouth and gums in the formation of dentures.

Other objects and important features of my invention will be more fully and clearly set forth in the following specification and claims.

In the drawings forming a part of this specification:

Figure 1 is a perspective view of my impression tray for use in connection with the lower teeth.

Figure 2 is a plan view of the impression tray illustrated in Figure 1.

orthodontic or partial impressions It is type of tray to aid the dentist in Ihe most difiicult operation plaster in sections is necessary.

It is very difiicult Miscalculation also often causes Furthermore, as the outside sur- Figure 3 is a perspective view of the reverse side of the impression tray of Figures 1 and 2.

Figure 4 is a perspective view of the removable portion of the impression tray of Figures 1, 2 and 3.

Figure 5 is a side elevational view of the removable portion of the tray illustrated in Figure 4.

Figure 6 is a perspective view of the impression or cast made by the impression tray of Figures 1, 2 and 3.

Figure 7 is a similar view to Figure 6, showing some of the sections of the cast impression broken away.

Figure 8 is a perspective view of my impression tray for use in connection with the upper teeth.

Figure 9 is a plan view of the impression tray illustrated in Figure 8.

Figure 10 is a perspective view of the reverse side of the impression tray illustrated in Figures 8 and 9.

Figure 11 is a perspective view of the cast impression made by the tray disclosed in Figures 8, 9 and 10.

Figure 12 is a longitudinal cross-section view of the. tray of Figure 8, a portion of the upper jaw, a section through the impression cast within the tray, and the wrench which is used in the separation of the removable portion of the tray from the remainder of the tray.

Figure 13 is a perspective view of my lower denture tray.

Figure 14 is a perspective view of the reverse side of the lower denture tray illustrated in Figure 13.

Figure 15 is a perspective view of my upper denture tray.

Figure 16 is a perspective view of the reverse side of the upper denture tray illustrated in 40 Figure 15.

Figure 17 is a perspective view of a cast impression made in one of w my impression trays showing my method of holding the opposite v buccal sections in place while the lingual sections are being removed.

Figure 18 shows the manner in which my lower denture tray is held in position during the setting of the impression compound.

vFigure 19 illustrates the manner in which the impression tray can be grasped for removal of the tray.

Figure 20 discloses the manner of holding the upper impression tray in position while the impression compound is setting.

Figure 21 illustrates my instrument for breaking apart the cast impression molds into various sections.

Figure 22 illustrates my instrument for cutting the grooves in the impression deeper when desired.

' My impression tray A is designed to contain an impression compound such as plaster of Paris, and to fit over the lower teeth, holding the plaster in position about the teeth until the same is set. As shown in the figures, the tray A is substantially U-shaped, with a handle projecting out radially from the center of the rounded closed end of the U.

The impression tray A is provided with an outer side wall II] on the base II forming the bottom of the tray. A pair of opposed innerside walls I2 also extend from the base I I, and "are date the rotatable pin I6.

ribs I5 on the removable section I4 slide in the grooves of the spaced ends I3 so that the section I4 is slidable and removable vertically, but is held in proper relationship to the walls l2.

As shown in Figures 4 and 5 of the drawings, the portion I4 is drilled vertically to accommo- A hearing washer I! at the bottom of the member I4, and a second washer I8 at the top of the member I4 which washer is riveted to the top end of the pin I 6, hold the portion I4 securely and rotatably to the pin I6.

A short length I6 of the pin I6 adjacent the lower bearing washer I1 is threaded, and the lower extremity I6" of the pin I6 is hexagonal to accommodate a wrench B by means of which the pin I6 may be rotated. The pin I 5 fits into a threaded opening I9 in the base H of the tray A in such a manner that by rotating the pin I6 the removable portion I4 of the tray A may be slid vertically between the spaced ends I3 of the inner side walls l2.

The inner surface 20 of the removable portion I4 which extends into the tray A is provided with transverse anchoring grooves 22 which are larger at the base thereof than on the surface 253. These grooves act as anchoring grooves for the plaster, as when the plaster sets the portion I4 cannot be removed from contact with the plaster impression until it is broken away.

The removable portion I4 acts as a means for causing the separation between the plaster and the tray A after the plaster has set. The portion I4 is the only portion of the tray A which is firmly embedded in the plaster. When the plaster is being set, the portion, I 4 is screwed down against the base II of the tray. When the plaster has hardened, the pin I6 is engaged by the wrench B and rotated. This rotation unscrews the pin I6 from. the base II, sliding the portion I4 vertically and separating the plaster cast from the tray A. The tray A may then be removed.

When a plaster impression is made in the mouth, it is necessary to break the impression into a number of sections in order to remove the plaster due to the outward taper of the teeth and the various angles at which the teeth project from the gums. It ismy desire to provide cleavage lines in the plaster cast or impression at which lines the cast will break more readily than at any other point. To provide such cleavage lines, I form ribs 23 projecting into the tray from the base II. The ribs 23 are formed with sides substantially parallel for a short distance from the base II and which taper to a point or single line at the top of each rib 23. The ribs 23 follow substantially the curvature of the lower row of teeth, and when in place may be held spaced slightly above the center line of the teeth between the cusps of the bicusp-ids and molars, or may extend approximately over the center line of the incisors and cuspids or the canine eminences and overthe cusps adjacent the lingual surfaces of the'bicuspids and molars. The dentist is provided with a series of trays of graded sizesand may select the tray in which the ribs 23 most nearly approximate the desired line of cleavage between the lingual and the buccal and labial sections.

Dividing ribs 24 extend inwardly from the outer side wall Illand'connect with the central dividing ribs 23; and ribs 25 extend inwardly from theinner spaced walls I2, also connecting with the'ribs 23. These ribs extendinto the cast impression to form lines of cleavage between various sections. The ribs 24 divide the right and left buccal sections from the labial section. The ribs 25 separate the right and left lingual sections from the anterior lingual section.

Figure 6 of the drawings illustrates a cast impression just after the tray A has been removed therefrom. The removable portion I4 of the tray, with its pin I6, may be seen embedded in the plaster forming the anterior lingual section of the impression. Figure 7 illustrates the same impression immediately after the right and left lingual sections are broken away. As the buccal and labial sections are removed more easily than the lingual sections, I provide a means for holding the right and left buccal sections in place while the right and left lingual sections are being removed, which means will be later more clearly described. The deep grooves 26 in the impression C formed by the ribs 23, and the grooves 21 formed by the ribs 24 and 25, divide th impression C into a number of sections having well defined cleavage lines and which may be easily separated into sections.

The handle portion 28 of the tray A is preferably formed flush with the outer surface of the base II, and projects from the labial portion of the outer side wall IQ of the tray A. The base ll of the tray is provided on its outer surface with a groove 90 extending partially around the tray A in a position corresponding to the position of the ribs 23 within the tray, or corresponding to the desired line of cleavage on the occlusal surfaces of the teeth.

My impression tray A is provided with a handle 39 similar to the handle 28 of the tray A. The tray A, however, is designed for making impressions of the upper teeth. The tray A is D-shaped rather than U-shaped, with the handle 30 extending from the rounded end of the D. This upper tray is designed to take the impression of both sides of the row of teeth, as well as the shape of the palate. The tray A is provided with an outer side wall 32 to enclose the buccal and labial portions of the impression, and a palatal border portion 33 adapted to extend closely adjacent the palate of the patient. The base 34 of the tray extends beneath the entire surface bounded by the outer side Wall 32 and the palatal border 33.

Ribs 35 extend upwardly from the base 34 and form a curved line substantially corresponding to the desired line of cleavage between the palatal portion and the buccal and labial portions. This line is preferably directly over the center line of the teeth between the cusps of the molars and the bicuspids or else over the cusps adjacent the buccal surfaces of the teeth. Auxiliary ribs 36 connect the outer wall 32 with the ribs 35 forming grooves 31 in the bucc-al surfaces of the impression C formed in the tray A, dividing the impression C into right and left buccal sections, a labial section, and a palatal section. The palatal section will readily be removed in a single piece, containing an impression of the lingual surface of each of the upper teeth. Grooves 38 in the impression C, formed by the ribs 35, divide the palatal section 39 from the right and left buccal sections 49 and 4| and the labial section 43.

The tray A is provided with a raised portion 44 in the base 34, somewhat corresponding to the shape of the palate, and upon this raise-d portion is mounted an anchoring member 45. This anchoring member is substantially D-shaped corresponding to the outer shape of the tray A,

and rests upon the base 34. A pin 46 extends through the anchoring member 45 and is rotatably secured in this member by bearing washers 4! and 48. The washer 48 is riveted in place by the end of the pin 46, holding the anchoring member rotatably between the washers 41 and 48. Pins 49 on the anchoring member 45 extend into holes 50 in the base 34 of the tray A, preventing rotation of the anchoring member 45 relative to the base 34. The pin 46 is provided with a threaded portion 46 adapted to screw into a threaded opening in the base 34. The extremity 46" of the pin 46 extending through the base 34 is hexagonal and may be engaged and rotated by a wrench B, as shown in Figure 12 of the drawings.

The anchoring member 45 is undercut along its forward and side surfaces, or over the rounded sides of its D-shape, as shown at 52. The rear surface of the member 45 is grooved at 54. Accordingly, the member 45 is securely embedded in the plaster when an impression is made. Thus the anchoring member provides a means of separating the impression C from the tray A when the plaster forming the impression has hardened. By merely rotating the pin 46 in one direction, the anchoring member will be separated from the tray A, carrying the tray away from the impression C.

Because of the variance in the shape of the palates of different patients, I provide a removable flexible stopper 55 for preventing any excess of plaster from running down the throat of the patient. This stopper 55 consists in a flexible double flap of rubber or other similar material having lugs 56 formed thereupon which are extendible into pairs of holes 51 formed. through the palatal border wall. The projections lock the stopper in place. The stopper extends up into contact with the palate, and may be trimmed off with scissors if desired to fit closely adjacent the palate, and to conform with the shape thereof.

The wrench B for separating the removable portion of the trays A and A from the trays may be seen in Figure 12 of the drawings. This wrench is provided with a short head 58 at right angles to the shank 59 for the accommodation of the hexagonal end of a pin I6 or 45". The head 58 is equipped with a rotatable socket 60 secured in place by a stem 62 riveted upon the rear end of the head 58. Bevel gear teeth are provided adjacent the socket 58 for engagement with a complementary gear 63 on the shaft 64. The rotatable end 65 is secured to turn with the shaft 64, and is held rotatable to the hollow shank 59 by means of a set screw 66 which engages in a circumferential slot 61 in a portion 68 of the end extending within the hollow shank 59. By holding the shank 59 the end 65 of the wrench may be operated to rotate the socket 69 and consequently the pin IE" or 4B". A hook 70 is formed on one end of the wrench B which hook may be inserted through an opening 12 through the hexagonal end [6" or 46" to assist in removing either the anterior lingual section of the impression mold C or the palatal section of the impression C from the mouth of the patient.

In Figures 13 and 14, I illustrate my denture tray D for the lower jaw. This tray is somewhat similar in general shape to the tray A, but contains no removable portion and no ribs for dividing the impression into sections, for in the preparation of dentures the impression of the gums and mouth may be made in a single piece.

the grooves, while the straight sides It is the usual process to place impression wax in a tray, make an impression in the modelling compound, remove it from the tray, and use the impression thus formed in the preparation. of the denture. I provide grooves I3 and I4 in the inner side wall Hand in the outer side wall I6 respectively to hold the wax impression in place. In this manner the impression is reinforced by the tray in the preparation of the denture, preventing breakage of the wax Walls. The conformation of the denture tray D may. be seen in Figures 13 and 14.

In Figures 15 and 16 of the drawings, I disclose an upper denture tray D. This tray is very similar in general shape to the impression tray A, but has no removable portions or ribs to divide the impression into sections. The handle I! is similar to the handle 39 of the impression tray A, and it also has a base I8 and an outer side wall 79 about the rounded sides of its D shaped body portion. A raised portion 80 is provided in the base 718 to conform with the general shape of the palate, and grooves 82 are formed in the wall I8 and in the edge 83 of the raised portion 80 of the base I3 to engage the impression wax within the tray to hold the impression in the tray during the formation of the denture. If it is desired, anchoring holes or indentations can be substituted for the grooves.

Each of my trays A, A, D and D is provided with means for facilitating the holding of the tray, both in position in the mouth to hold the tray while the impression material is setting and in removing the tray from the mouth. The handles 29, 39,11 and 84 of'the trays A, A, D and D respectively, provide a means of holding the trays while preparing the impression material therein, and for general use in holding the tray. Each side of the handle is knurled for providing a better grip. Oppositely disposed concave knurled portions 85 on the outer side walls of the tray provide a grip whereby the tray may be readily removed from the mouth, as shown in Figure 19 of the drawings. On the base I I of the tray A, on the outer surface thereof, and on opposite sides of the center line, are two concave knurled surfaces 85 against which the fingers may engage to hold the tray A in position while an impression is being made. Similar surfaces are provided on the trays A, D, and D. The use of the knurled surfaces 96 may be seen in Figure 18 of the drawings.

Figure 20 shows a finger engaging surface formed in the shape of a pocket 81. Such a surface is found in the trays A and D, and is particularly adapted for accommodation of a finger to hold the tray up against the upper teeth. The arrangement of these surfaces is a distinct advantage over any tray holding construction with which I am familiar.

"The tool E illustrated in Figure 21 of the drawings is an instrument which may be used for separating the sections of the mold. By pressing togetherthe handle levers 88, the flat jaws 89 are separated. By inserting these jaws in one of the grooves formed in the mold for the division of the impression into sections, and pressing together the handle levers 88, the sections will be separated very nearly along the desired line of cleavage. As will be notedin the drawings, one side of each jaw 89 is curved while the'other side of each jaw is straight. The curved sides of the jaw are used in the curved portions of are used in the'straight portions. r

'tially right angles to the handle.

In making impressions with the use of my apparatus, it is only necessary to fill the tray with the proper amount of plaster, insert it in position properly in the patients mouth, and hold the tray until the plaster has set. The proper size of tray may be determined by trial, or by a caliper measurement of the width between the lines of cleavage on occlusal surfaces of the teeth. The proper position of the tray may be readily determined by the grooves 29 in the trays A and the similar grooves 90 on the trays A. The teeth and mouth, as well as the tray used, may be treated with a separating material to facilitate separation of the plaster from these parts.

When the plaster has set, the wrench B is applied to the pin I6 or 49, and the tray is'separated from the plaster. If the impression is being made of the upper teeth, the tool E is inserted between the various sections of the impression and the sections removed. Usually the buccal and labial sections are removed prior to the removal of the palatal section, which is removed by the hook III on thewrench B.

In making impressions of the lower teeth, the buccal and labial sections are usually easily removed, so it is desired to first remove the lingual section. The tool F is inserted to clamp the right and left buccal sections rigidly in place. The tool F comprises a pair of crossed. and pivoted levers 9| and 92, which are provided with finger engaging loops 93 and 94, and which are pivotally connected to clamping plates 95 and 96 at the other extremities thereof. The clamping plates 95 and 96 have knurled surfaces 9'! which engage the opposite sides of the right and left buccal sections 98 and 99. While these sections are being rigidly held in this manner, and locked by means of the locking arrangement I90 between the levers 99 and 92, the right and left lingual sections I02 and I03 may be readily removed by breaking with the tool E along the indicated lines of cleavage, and removing the sections.

By this method, impressions may be made in a very few minutes, while with the present method often a long period of time is necessary before the plaster can be removed. The grooves in the applicants impression eliminate estimation of the proper lines of division of the sections. Definite, predetermined sections are formed, which may be put together in the tray from which they were cast, after removal tom the mouth. Nausea created by long periods of time elapsing before the removal of the plaster from the mouth can be obviated, and more perfect impressions may be made. Cutting into the plaster is only advisable over a long space devoid of teeth, and this cutting is not always necessary. Thus the danger of cuting into the gums is entirely eliminated.

To facilitate the operation of cutting the grooves in the impression deeper when desired over long spaces where teeth have been extracted, I provide the tool G which is provided with a handle I and a cutting blade I96 at substan- Enlarged shoulders IU'I one of which is positioned on either side of the blade II'IB limit the distance to which the blade may extend into the impression, thus making it impossible to cut into the gums.

Knurled surfaces I 08 on the handle I05 and a 7 described the principles of operation of my dental impression apparatus and the methods of operation in the use of the same, and while'I have em deavored to set forth the best embodiment thereof, I desire to have it understood that this is only illustrative of a means of carrying out my invention, and that obvious changes may be made 5 within the scope of the following claims without departing from the spirit of the invention.

I claim:

1. A dental impression tray including, a container for impression material shaped to fit within the mouth, a removable portion on said container, means on said removable portion to anchor said removable portion to impression material within said container, and means for separating said removable portion from said container, said anchor means preventing separation of said impression material from said removable portion.

2. A dental impression tray including, a container for impression material, walls on said container, a removable section in one of said walls, 20 means on said removable section for anchoring said section to impression material in said container, and means for separating said removable section from said container to separate the impression material from the remainder of said con- 25 tainer, said anchoring means engaging said impression material against removal without breakage of a portion of said impression material.

3. A dental impression tray including a container for impression material, a removable por- 30 tion on said container, means on said removable portion to anchor said removable portion to impression material within said container, said anchor means preventing separation of said impression material from said removable portion, 5 and means in said container for separating said removable portion and said impression material from said container.

4. A dental impression tray including a base,

side Walls for containing impression material therebetween, and removable means on one of said side walls, said means being embedded in said impression material and preventing separation of said material from said means, for holding said impression material removably in said tray.

5. The method of forming a dental impression consisting in inserting impression material in a tray, holding the tray in position to obtain the impression, embedding a portion of the tray permanently in the impression material preventing separation of said impression material from said portion, removing the unembedded portion of the tray, and then removing the impression material in sections in one portion of which is embedded said portion.

6. A dental impression tray including a base, side walls on said base, a removable section in said tray, means for moving said removable section in one direction away from said base, and means for anchoring said removable section in impression material so that movement of said removable section with respect to said tray cannot disengage said removable section from said impression material but will separate said material from the remainder of said tray.

7. A dental impression tray including a base, side walls on said base, a removable section in said tray, means for moving said removable section with respect to said base in one direction, means in said removable section presenting a more secure anchor for impression material than is provided by said base and side walls, so that movement of said removable section away from said base will separate the impression material in its entirety from said base.

ALFRED K. SIMMONS. 

